When checking out tile sets on the Mac IDE I thought I'd try making a tile set from a SWF and Spine sprite, turns out we don't block this and it does work (to a degree). Running your game with a SWF Sprite Tile Set will crash the runner as seen in the attached project and log however running with a Spine Sprite Tile Set will work although you've now lost the actual purpose of the Spine Sprite.

Ideally we should block you at the very first point of entry eg when selecting the sprite so that you can't even reach the same conclusions I have.

Steps To Reproduce

1) Create a project
2) Create a tile set
3) Create a sprite
4) Import spine/swf sprite
5) Drag the sprite onto the dropper area for the tile set preview window